1. Field of the Invention
The present invention relates to a photosensitive material advantageously employable for color proof in color proofing or display.
2. Description of Prior Art
There are known image transfer processes comprising imagewise exposing a photosensitive transfer material comprising an undercoat layer composed of an organic polymer, a coloring material layer and a photosensitive layer provided on a temporary support to light, developing it to form a color image on a peel layer and transferring the image to a given support (permanent support) using an adhesive (see, Japanese Patent Publication Nos. 46(1971)-15326 and 49(1974)-441). These processes have advantages in that they can be used as color proof for various procedures such as overlay type proof and surprint type proof. However, these processes have disadvantages in that an adhesive must be used for every transferring procedure and hence the processes are complicated and in that there is a difficulty in keeping the accuracy of registration in transferring each color.
To eliminate the complicated procedures of the process, there are proposed methods wherein after the formation of an image, the image is transferred to a permanent support under the application of heat and pressure (see, Japanese Patent Provisional Publication Nos. 47(1972)-41830, 48(1973)-9337 and 51(1976)-5101). Particularly, Japanese Patent Provisional Publication No. 51(1976)-5101 discloses that a hot-melt polymer layer as an adhesive is provided on a permanent support and Japanese Patent Provisional Publication No. 47(1972)-41830 proposes that an image is transferred directly to a permanent support such as art paper or coated paper.
However, these processes have still various disadvantages in that the final image is transferred to a permanent support in such a manner that the right and the left are reversed against the original image and in that when a hot-melt polymer is used as an adhesive, the melting point thereof is usually high and hence the transferring temperature must be high so that the dimensional stability of the support is deteriorated by the action of heat, and the deviation of colors from one another in registration is caused in transferring each color. When a hot-melt polymer having a low melting point is used as an adhesive, there are caused problems that after the formation of an image, sticking is observed, or the surface thereof is liable to be marred.
As a method for eliminating the above-described disadvantages, there is proposed in Japanese Patent Provisional Publication No. 59(1984)-97140 a process wherein an image is transferred to a temporary image receiving sheet before the image is transferred to a permanent support. This process includes steps of: preparing a temporary image receiving sheet provided with an image receiving layer composed of a photopolymerizable material on a support; transferring an image of each color to the temporary image receiving sheet before the image of each color is transferred to a permanent support; re-transferring said image to a permanent support; and exposing wholly it to light to cure the transferred photopolymerizable image receiving layer.
The above-described image transferring process using the temporary image receiving sheet (hereinafter referred to simply as image receiving sheet) is very effective in eliminating the aforementioned problems. In more detail, there are given the following advantages. An erect image against the masked original can be obtained on the permanent support. Since an ethylenically unsaturated polyfunctional monomer serving as a photopolymerizable substance is incorporated in the photopolymerizable image receiving layer of the image receiving sheet, the photopolymerizable image receiving layer itself is soft, transferring can be carried out at a low temperature and after transferring, it can be exposed wholly to light to cure it. Thus, there are given advantages that after the transfer of the image, sticking is not observed and the final image has high resistance to marring.
As the photosensitive transfer material used in the image transferring method, there is generally used a photosensitive material comprising an undercoat layer (functioning as a peel layer) composed of an organic polymer, and a coloring material-containing photosensitive layer (or a laminate composed of a coloring material layer and a photosensitive layer) in order in the form of a laminate.
There have been proposed various materials as undercoat layer-forming materials for the photosensitive material. Among them, high-molecular polymer materials mainly composed of an alcohol-soluble polyamide are preferred from the viewpoints of such characteristics that they have proper adhesion to the temporary support, but can be peeled therefrom, and while they are non-tacky at room temperature, they become tacky or fusable by heating.
Though the high-molecular polymer materials mainly composed of an alcohol-soluble polyamide are excellent materials for the formation of a peel layer from the viewpoints of the above-described functions, the present inventors have found that there are caused problems in the course of the production of the photosensitive material, because they are soluble in alcohols.
In the formation of a coloring material-containing photosensitive layer or a coloring material layer on the peel layer, there are often used coating solutions containing an alcohol such as methanol, ethanol or propanol as a solvent. Hence, there is often caused that during coating procedure, a part of the surface of the peel layer is dissolved and a part of a coloring material is introduced into the peel layer. In such a case, color fogging is caused by the coloring material introduced into the peel layer and the quality of the obtained image deteriorates.
Further, the use of pigments, not dyes, as the coloring material is effective in preventing color fogging from being caused in the non-image part. In the case where naphthoquinone diazide compounds are used as photosensitive materials, the foot of the absorption spectrum of said compounds extends to reach the visible light region so that when the compounds are introduced into the peel layer, color fogging is caused and the quality of the image lowers.